Condensation temperature measuring apparatus



W. H. HOWE Feb. 23, 1943.

CONDENSATION TEMPERATURE MEASURING APPARATUS Filed Sept. 23, 1939INVENTOR 1 M MFAEO h. /-/0 w. 61/12), EM 1' AA7WAQ ATTORNEYS PatentedFeb. 23, 1943 CONDENSATION TEMPERATURE MEASURING APPARATUS Wilfred H.Howe, Sharon, Mass, assignor to The Foxboro Company, Foxboro, Mass., atcorporation Massachusetts Application September 23, 1939, Serial No.296,211

9 Claims.

This invention relates to indicating, recording, and controllingapparatus, and more in particular to apparatus for aiding in themeasurement of the condensing temperature of a flowing stream of acondensable vapor or gas such, for example, as steam.

An object of this invention is to provide apparatus for obtaining acontinuous sample of a stream of fiuid from which a record of itscharacteristics may be obtained. A further object is to provideapparatus of the above character for continuously removingnon-condensable gas, such as air, from the vicinity of a thermometerbulb responsive to the condensing temperature of a condensable gas suchas steam. A still further object is to provide apparatus of the abovecharacter which is sturdy in construction and dependable in operationfor the continuous measurement of the condensing temperature of aflowing stream of a condensable gas containing non-condensable gases.Other objects will be in part obvious and in part pointed outhereinafter.

The invention accordingly consists in the features of construction,combinations of elements, arrangements of parts, and in the severalsteps and relation and order of each of the same to one or more of theothers, all as will be illustratively described herein, and the scope ofthe application of which will be indicated in the following claims.

In the accompanying drawing, in which are shown two of the variouspossible embodiments of this invention:

Figure 1 is a sectional view with a portion of the connecting pipebroken away; and

Figure 2 is a view similar to the lower portion of Figure 1 and showinga modified form of tube construction.

In steam heated apparatus, utilizing the condensation of steam, theuseful temperature for measurement and control purposes is thecondensing temperature of the steam; this temperature is termed thesaturation temperature. This temperature is the temperature thatsaturated steam would have at the pressure of the steam in theapparatus. Often, however, the temperature of the steam flowing to theapparatus is higher than its saturation temperature.

Steam temperature at the point of supply exceeds the saturationtemperature if the steam contains superheat; that is, if the steam is ata temperature above the condensing tempera ture corresponding to thesteam pressure of the system.

To remove this excess heat and obtain the saturation temperature, it hasbeen the practice to Withdraw steam from the steam line into acondensing chamber, the pressure in which is the same as that in thesteam line. In the condensing chamber the excess heat carried by thesteam is dissipated, and the steam is caused to condense. Thetemperature of this condensing steam is measured to obtain thetemperature desired. However, if a non-condensable gas such as air ispresent in the steam, the air tends to accumulate in the condensingchamber to a much greater concentration than that existing in theoriginal steam-air mixture in the steam line. When such an accumulationof air is present in the condensing chamber, the condensing temperaturemeasured is lower than the actual condensing temperature of thesteam-air mixture in the steam line, and the temperature reading istherefore incorrect. In the present embodiment, this problem is solvedby causing a circulation within the condensing chamber sufiicient towithdraw air from the condensing chamber to keep the air ,in thesteam-air mixture therein from concentrating to a point over thatexisting in the steam line where the desired temperature reading willnot be obtained. Preferably this circulation is adjustable and does notinduce sufiicient flow to interfere with the dissipation of the heat ofsuperheat and the normal condensation of the steam upon the thermometerbulb.

Illustratively, in Figure 1 of the drawing steam flows from left toright in a pipe 2. A condensing chamber is attached to the pipe 2through a T-coupling joint 4 into which is threaded connecting pipe 6 atright angles to pipe 2. Pipe 6 is connected at its upper end through aneccentric coupling 8 to a larger pipe I 0, the joints being welded. Theupper end of pipe l0, covered by a T-cap l2, forms a thermometer well,indicated at l9. Extending downwardly into this well is a thermometer.bulb l8.

From the top of thermometer bulb I8 a tube 22 extends, which tube may beconnected with a suitable recorder or indicator not shown, Thethermometer bulb is supported by a ridge 24 at its upper end clampedbetween the adjacent beveled surfaces of a pair of nested screw sleevesl6 and 20; screw sleeve 16 is threaded. into T-cap l 2, and screw sleeve20 in turn is threaded into screw sleeve 16. At the left, T-cap l2 maybe connected through a pipe M to a pressure gauge (not shown).

The upper end of the tube is open to the interior of T-cap i2, and thelower end extends into the path of the flowing steam in pipe 2. Thelower' end of the tube is cut away,-as indicated at 28, at an angle of60140 provide an opening which faces downstream of the flowing steam.

During operation the interior of the condensing chamber is, of course,exposed to the same pressure that exists in the steam line 2, and theinterior walls of the condensing chamber are in contact with the samesteam that exists in the pipe 2. The condensing chamber, however, is notinsulated from heat flow and so dissipates some of the heat of the steamin the condensing chamber, thereby not only removingthe superheat fromthe steam but also causing condensation of some of the steam in thechamber. This condensation, of course, causes fresh steam to enter fromthe pipe 2, the condensate flowing down the walls of the condensingchamber back into pipe 2.

In addition to this circulation caused by the condensing oi the steam inthe condensing chamber, the steam flowing past the end of the tube 28reduces the pressure in the lower end of the tube below that pressureexisting at the top of the condensing chamber sufficiently to cause airand steam to flow down through the tube to maintain a steam-air mixturein the vicinity of the bulb l8 substantially equal to' that existing inthe main steam line..

As pointed out above, as the steam flows upwardly toward bulb I8, thesuperheat is dissipated through the walls to the atmosphere, and steamcondenses in the vicinity of the bulb. AE- cordingiy, the flow inducedby the tube should not be great enough to interfere with the compieteremoval of this superheat and the steam condensation. To this end, theangle of the tube with respect to the steam flow in the pipe 2 may beadjusted by rotating the pipe 6 in the T-coupling 4 to adjust theeflfective pressure drop set by the. tube between the pressure at itstop and the pressure in the steam line 2. Such an adiustment isdesirable to meet different conditions under which the apparatus may beused. Such difierent conditions may be, for example, different steamvelocities in the steam line 2.

In obtaining this adjustment, as shown in Figure 2, a modified form oftip on the tube 26 may be used. Thus, a disc 38 is welded to theupstream side of the tip 28 to increase the effectiveness of the tubewhen the velocity of the steam in the steam line 2 is low.

As many possible embodiments may be made of the mechanical features ofthe above invention and as the art herein described might be varied invarious parts, allwithout departing from the scope of the invention, itis to be undcrstood that all matter hereinabove set forth, or shown inthe accompanying drawing, is to be interpreted as illustrative and notin a limiting sense.

I claim:

1. In apparatus for measuring the condensing temperature of a stream ofcondensable gas flowing through a pipe and containing noncondensablegases, the combination with said pipe of a dead-end condensing chamberopening into and extending from said pipe, said condensing chamber beingprovided to remove superheat from the condensable gas entering saidcondensing chamber, a temperature responsive bulb located in the deadend 01 said condensing chamber and responsive to the condensingtemperature of the condensable gas condensing thereon, meanaproviding apassageway opening into said dead end and into said stream of gas, theopening of said passageway into said stream of gas being so located withrespect to the direction of flow of said stream of gas as to cause acontinuous flow of gas in 'said passageway.

2. In apparatus for measuring the condensing temperature or acondensable gas flowing through a pipe, the combination of, acondensation chamber connected to receive the condensable gas from thepipe and adapted to remove heat from the condensable gas to therebycause condensation within said condensation chamber, a temperatureresponsive device positioned within said condensation chamber, and atube extending from said condensation chamber to said pipe, the end ofsaid tube at said pipe being so located with respect to the direction offlow of gas in said pipe as to cause a flow of gas through said tube tocause desired gas circulation in the vicinity of said temperaturemeasuring device.

- 3. In apparatus of the class described, the combination of, a pipecarrying a stream of fluid material such as steam, a condensing tubeextending substantially at right angles to said pipe and connected atone end to said pipe, means for closing the other end of said condensingtube to form a condensing chamber, and a conduit having one end locatedin said condensing chamber and the other end extending into the streamof fluid, the extended end of said conduit being provided with anopening so located with respect to the direction of flow of fluid insaid stream as to cause said conduit to deliver fluid from saidcondensing tube to the stream of fluid.

4. In apparatus for measuring the condensing temperature of asuperheated flowing condensable gas such as steam containingnon-condensable gases such as air, in combination, a dead-end condensingchamber connected directly to a line through which the gas mixture isflowing for removing superheat from and condensing a portion of the gasmixture entering said chamber, a thermometer bulb in said chamber formeasuring the condensing temperature of the condensable gas. a tube insaid condensing chamber extending from its dead end into the stream 01flowing gas mixture for continuously removing from the chambernon-condensable gas entering with the condensed condensable gas, andmeans to adjust said tube in said stream to regulate circulation of thegas mix ture through the condensing chamber induced by the tube.

5. In apparatus of the class which is used for measuring thecondensation temperature of flowing steam in which a condensing chamberis connected directly to the steam line and as the steam flows into thecondensing chamber it loses any superheat which it has and a portion ofthe steam condenses, and wherein the temperature of the condensing steamis measured. the combination with said condensing chamber of a tubewhich extends from said condensing chamber to the stream of flowingsteam, the end of said tube which is in contact with the stream offlowing steam being so located with respect to the direction of flow ofsteam as to cause the withdrawal of non-condensable gases from thevicinity where the temperature is being measured, and means for changingthe location oi the end of said tube to vary the rate of withdrawal ofsaid non-condensable gases.

6. In apparatus of the class which is used for measuring thecondensation temperature of flowing steam in which a condensing chamberis connected directly to the steam line and as the steam flows into thecondensing chamber it loses any superheat which it has and a portion ofthe steam condenses, and wherein the temperature of the condensing steamis measured, the combination with said condensing chamber of a tubewhich extends from said condensing chamber to the extreme of flowingvsteam to withdraw gases from the vicinity where the temperature is beingmeasured, the end of said tube which extends into the stream being cutat an angle to provide an opening lacing downstream of the direction offlow.

7. In apparatus of the class which is used for measuring thecondensation temperature of flowing steam in which a condensing chamberis connected directly to the steam line and as the steam flows into thecondensing chamber is loses any superheat which it has and a portion ofthe steam condenses, and wherein the temperature of the condensing steamis measured, the combination with said condensing chamber of a tubewhich extends from said condensing chamber to the stream of flowingsteam to withdraw gases from the vicinity where the temperature is beingmeasured, the end of said tube which extends into the stream beingprovided with a disc positioned on the upstream side of the tube withrespect to the fiow of the steam to reduce the pressure in the vicinityof the end of the tube below the static pressure of the steam.

8. In apparatus of the class described, the combination of, a pipecarrying a stream of condensable vapor such as steam and contaminated byvapor non-condensable at the condensing temperature of the main portionof the vapor, a condensing tube connected at one end to said pipe, meansclosing the other end of said condensing tube to form a condensingchamber, said condensing chamber being adapted to condense the vaportherein and to return the condensate to said stream, and a tubeconnecting said condensing chamber to the stream of vapor and having oneend so connected into the stream of vapor that the effective pressure atsuch end is lower than the effective pressure at the other end thereof,whereby a continuous flow of vapor is maintained from the condensingchamber through the tube into the stream of vapor to prevent collectionof said non-condensable vapor in said condensing chamber.

9. In apparatus of the class described, the combination of, a pipecarrying a stream of condensable vapor such as steam and contaminated byvapor non-rondensable at the condensing temperature of the main portionof the vapor, a heat dispensing condensing tube connected at one end tosaid pipe and closed at the other end, said condensing tube therebyforming a condensing chamber to condense therein vapor entering saidcondensing chamber from said pipe, and a tube having one end terminatingin said condensing tube and having its other end terminating in saidstream of vapor in such a manner as to maintain a pressure differencebetween the ends or the tube and a resulting continuous flow throughsaid tube, whereby the accumulation of non-condensable vapor isprevented in said condensing chamber.

WILFRED H. HOWE.

